[Softwires] Checksum neutrality and L4-protocol independence
Rémi Després <despres.remi@laposte.net> Mon, 06 February 2012 08:52 UTC
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From: Rémi Després <despres.remi@laposte.net>
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Date: Mon, 06 Feb 2012 09:52:04 +0100
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To: Ole Trøan <otroan@employees.org>
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Subject: [Softwires] Checksum neutrality and L4-protocol independence
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Le 2012-02-05 à 10:05, Ole Trøan a écrit : ... >>> any A+P solution requires support for L4 protocols to extract ports. >>> L4 checksum rewrite, as well as port extraction will have to be supported for all new L4 protocols. >>> the L4 checksum rewrite approach can work with any checksum algorithm. >>> that said, do we really think NAT44s will be upgraded to support any new L4? >> >> Imagine a variant of the SCTP of RFC4960 is introduced where the TCP-like checksum MAY be used to facilitate its deployment, say SCTP-bis (not a bad idea IMHO, but here just a hypothesis to answer your point). >> => 4rd-H would be compatible with it without any evolution; RFC6145 would need an upgrade to support it. >> >> Upgrading NAT44s to support this SCTP-bis would be trivial (ports as the same place as usual can be mapped as usual. > > my point is that MAP is L4 aware anyway, and has to be modified to support any new transport protocol. since code modifications have to be made, then having a checksum neutral function at the network layer doesn't help much. you still need to change code. L4 rewrite is also more flexible in that it will support _any_ checksum algorithm, and most importantly is already implemented in every node. Thus, you continue to negate that 4rd-U would support without any change a protocol such as, for example, a SCTP variant using TCP-like checksum instead of its CRC32c checksum. This negation is AFAIK based on a lack of understanding: - UDP, TCP, DCCP, SCTP have the same places for port their fields, but have their own places for their checksum fields. - A solution based on L4 checksum adjustment MUST know _for each protocol_ where checksum fields are placed. - A solution based on checksum neutrality of IPv6 addresses doesn't need to know where checksum fields are placed. - For address sharing, knowing places of port fields is sufficient. I added Dan as destination of this mail, hoping to have his comment. RD
- [Softwires] Moving forward with 4rd-T, 4rd-E & 4r… Alain Durand
- Re: [Softwires] Moving forward with 4rd-T, 4rd-E … Mouli Chandramouli (moulchan)
- Re: [Softwires] Moving forward with 4rd-T, 4rd-E … Ole Trøan
- Re: [Softwires] Moving forward with 4rd-T, 4rd-E … Rémi Després
- Re: [Softwires] Moving forward with 4rd-T, 4rd-E … Alain Durand
- Re: [Softwires] Moving forward with 4rd-T, 4rd-E … Ole Trøan
- Re: [Softwires] Moving forward with 4rd-T, 4rd-E … Rémi Després
- Re: [Softwires] Moving forward with 4rd-T, 4rd-E … Ole Trøan
- Re: [Softwires] Moving forward with 4rd-T, 4rd-E … Ole Trøan
- Re: [Softwires] Moving forward with 4rd-T, 4rd-E … Rémi Després
- Re: [Softwires] Moving forward with 4rd-T, 4rd-E … Rémi Després
- Re: [Softwires] Moving forward with 4rd-T, 4rd-E … Tina TSOU
- Re: [Softwires] Moving forward with 4rd-T, 4rd-E … Rémi Després
- Re: [Softwires] Moving forward with 4rd-T, 4rd-E … Ole Trøan
- Re: [Softwires] Moving forward with 4rd-T, 4rd-E … Ole Trøan
- [Softwires] MAP & 4rd-U - Preserving freedom of s… Rémi Després
- Re: [Softwires] MAP & 4rd-U - Preserving freedom … Ole Trøan
- [Softwires] Checksum neutrality and L4-protocol i… Rémi Després
- [Softwires] MAP & 4rd-U - Robust Renumbering avoi… Rémi Després
- Re: [Softwires] MAP & 4rd-U - Robust Renumbering … Ole Trøan
- [Softwires] MAP and 4rd-U - how to try to converge Rémi Després
- [Softwires] MAP and 4rd-U Alain Durand
- Re: [Softwires] MAP and 4rd-U Ralph Droms
- Re: [Softwires] MAP and 4rd-U Ole Trøan
- Re: [Softwires] MAP and 4rd-U Reinaldo Penno
- Re: [Softwires] MAP and 4rd-U Jacni Qin
- [Softwires] MAP and 4rd - Feature comparison table Rémi Després
- Re: [Softwires] MAP and 4rd - Feature comparison … Rémi Després
- Re: [Softwires] MAP and 4rd - Feature comparison … Ole Trøan
- Re: [Softwires] MAP and 4rd - Feature comparison … Xing Li
- Re: [Softwires] MAP and 4rd - Feature comparison … Rémi Després
- Re: [Softwires] MAP and 4rd - Relationship with S… Rémi Després
- Re: [Softwires] MAP and 4rd - Feature comparison … Ole Trøan
- Re: [Softwires] MAP and 4rd - Feature comparison … Rémi Després
- Re: [Softwires] Checksum neutrality and L4-protoc… Maoke
- Re: [Softwires] Checksum neutrality and L4-protoc… Rémi Després
- Re: [Softwires] Checksum neutrality and L4-protoc… Maoke
- Re: [Softwires] Checksum neutrality and L4-protoc… Rémi Després
- Re: [Softwires] Checksum neutrality and L4-protoc… Maoke
- Re: [Softwires] Checksum neutrality and L4-protoc… Washam Fan
- Re: [Softwires] Checksum neutrality and L4-protoc… Rémi Després
- Re: [Softwires] Checksum neutrality and L4-protoc… Maoke
- Re: [Softwires] Checksum neutrality and L4-protoc… Maoke
- Re: [Softwires] Checksum neutrality and L4-protoc… Rémi Després
- Re: [Softwires] Checksum neutrality and L4-protoc… Maoke
- Re: [Softwires] Checksum neutrality and L4-protoc… Rémi Després
- Re: [Softwires] Checksum neutrality and L4-protoc… Maoke
- [Softwires] 答复: MAP and 4rd-U Huangjing
- Re: [Softwires] MAP and 4rd - Relationship with S… Xing Li
- Re: [Softwires] MAP and 4rd - Relationship with S… Rémi Després
- Re: [Softwires] MAP and 4rd - Relationship with S… Xing Li
- Re: [Softwires] MAP and 4rd - Relationship with S… Rémi Després
- Re: [Softwires] MAP and 4rd - Relationship with S… Rajiv Asati (rajiva)
- Re: [Softwires] MAP and 4rd - Relationship with S… Rémi Després
- Re: [Softwires] MAP and 4rd - Relationship with S… Xing Li
- Re: [Softwires] MAP and 4rd - Relationship with S… Rémi Després
- Re: [Softwires] MAP and 4rd - Relationship with S… Wojciech Dec
- Re: [Softwires] MAP and 4rd - Relationship with S… Rémi Després
- Re: [Softwires] MAP and 4rd - Relationship with S… Wojciech Dec
- Re: [Softwires] MAP and 4rd - Relationship with S… Rémi Després
- Re: [Softwires] MAP and 4rd - Relationship with S… Wojciech Dec
- Re: [Softwires] MAP and 4rd - Relationship with S… Rémi Després